I have a GeForce GT 740 graphics card installed and am running a clean install of 15.10. I was running the stock (X.Org X server) graphics driver installed by Ubuntu. Everything was great, shutdown and reboot was fast (near instantaneous) and booting was quick (running off a SSD). I enabled the Nvidia proprietary driver from the Software & Updates app to version 352.63 fro nvidia-352 (proprietary, tested). Since then, the system runs fine but shutdown and restarting takes about 60 seconds (instead of 2 seconds). When I try to restart or shutdown, I get a black screen and a long pause until the system reboots.
How can I fix this whilst keeping Nvidia's drivers (I believe they are required for Steam, which is not yet installed).
Thanks,
I had the same problem on fedora. I installed fedora in legacy mode not uefi and disabled intel graphic card in bios before installation nvidia drivers and now the system reboots very fast.
Try the [Additional Drivers] application from the unity launcher. I had the same problem with the 341.62 driver that the NVIDIA website recommends for GTX 650, but they went away after installing the 364.5 driver from the app.